1. Field of the Invention
The present invention is related to a communications network of interconnected servers and more particularly to, routing calls located anywhere in or out of a communications network such as to a public or private network and transporting digit string sequence carrier information.
2. Background Description
Carrier identification codes (CICs) are numeric codes that enable local exchange carriers (LECs) providing interstate interexchange access services to identify the interstate interexchange carrier (IXC) that the originating caller wishes to use to transmit its interstate call. LECs use the CICs to route traffic to the proper IXC and to bill for interstate access service provided. CICs enable callers to choose a telecommunications service provider, both by presubscription and by dialing a carrier access code, or CAC, that incorporates the carrier's unique CIC. Between 1983 and 1998, CICs were unique three-digit codes (XXX) and CACs were five-digit codes incorporating the CIC (10XXX).
However, in 1998, in order to increase the number of CICs available for assignment, four-digit CICs replaced three-digit CICs. With the four-digit CIC, CACs become seven-digit codes. IXCs that had three-digit CICs did not get new codes. Rather, an initial zero was added to their old three-digit CIC (i.e., 0XXX) to make it a four-digit CIC. In addition, a “1” was added to the end of the CAC prefix (i.e., 101 0XXX). Consequently, some carriers advertised the new CAC as a “10 10 XXX” number. Thus, a telephone caller can “dial around” a presubscribed long distance or local toll telephone carrier to reach another carrier by dialing a seven-digit CAC, e.g., in the U.S., (101 XXXX)+1+Area Code+Number.
However, when a private network caller enters a CAC/CIC, the call is routed over the private network to a gateway server to egress to the public network. The CAC/CIC combination is included in the digit string. However, including this seven digit CAC/CIC can cause problems. For example, the additional 7-digit CAC/CIC may cause the digit string to exceed the allowed field length in the server, causing the server to truncate the digit string, mis-routing the call or even resulting in call failure. The public network gateway server may not be able to parse the digits from the string correctly, also causing the call to be mis-routed or call to fail. This string length problem is further exacerbated if the private network requires an egress code (e.g., 9) for egressing to a public network, and worse still, when the number includes international access and country codes.
Also, including CAC/CIC digit values in the routing dial plan digit string patterns increases the number of entries in the routing dial plan exponentially. This increase is proportionate to the number CICs that exist (which has increased tenfold with the change from a three-digit CIC to four digit) and number of digit pattern strings in the customer dial plan. Further, CICs may change very frequently, i.e., due to additions, deletions caused by fluctuating Carrier businesses. These changes require time-consuming and costly dial plan administration.